.unload()

This method is a shortcut for .on( "unload", handler ).

The unload event is sent to the window element when the user navigates away from the page. This could mean one of many things. The user could have clicked on a link to leave the page, or typed in a new URL in the address bar. The forward and back buttons will trigger the event. Closing the browser window will cause the event to be triggered. Even a page reload will first create an unload event.

Any unload event handler should be bound to the window object:

$( window ).unload(function() {
  return "Handler for .unload() called.";
});

This event is available so that scripts can perform cleanup when the user leaves the page. Most browsers will ignore calls to alert(), confirm() and prompt() inside the event handler. The string you return may be used in a confirmation dialog, but not all browsers support this. It is not possible to cancel the unload event with .preventDefault().

• As the .unload() method is just a shorthand for .on( "unload", handler ), detaching is possible using .off( "unload" ).

A function to execute when the event is triggered.

A plain object of data that will be passed to the event handler.

A function to execute each time the event is triggered.

To display an alert when a page is unloaded:

$( window ).unload(function() {
  return "Bye now!";
});